The present invention generally relates to a steering lock assembly and, more particularly, to a steering lock assembly of a type utilizing a cylinder lock and a steering shaft lock operatively associated with the cylinder lock for selectively locking and unlocking an automobile steering shaft.
The British Pat. No. 1,512,809, published on June 1, 1978, discloses a steering column lock wherein a cam member for transmitting a rotation of a barrel forming a key plug part of the cylinder lock to a locking member for selectively locking and unlocking an automobile steering shaft is integrally formed with the barrel. However, the cam member used therein is of a size larger in diameter than that of the barrel and, therefore, assembly of the cylinder lock used therein necessitates the employment of a separate sleeve as the outer cylinder lock part for rotatably accommodating therein the barrel. This patent also discloses the employment of a retaining mechanism for retaining the locking member in an unlocked position once the locking member has been moved thereto by the cam member in response to the rotation of the barrel in one direction and so long as the key is not removed or withdrawn from the barrel even though the latter has subsequently been rotated in the reverse direction back to the original position, but permitting the locking member to return to a locked position upon withdrawal of the key from the cylinder lock. This retaining mechanism employed therein comprises a spring-loaded plunger, the operation of which is controlled by an axial movement of the barrel.
The cylinder lock which does not require the use of the cylinder outer or sleeve is disclosed, for example, in the British Pat. No. 1,455,444, published on Nov. 10, 1976. However, since this patent is directed to means for preventing a subassembly of the cylinder with the barrel of the cylinder lock from being removed by an unauthorized person, this patent is silent as to the details of how the cylinder lock is operatively associated with the locking member and also the details of the bolt retaining mechanism.
An example of prior art steering lock assembly which appears more pertinent to the present invention is shown in FIGS. 1 and 2 of the accompanying drawings in a longitudinal sectional view and a cross-sectional view taken along the line II--II in FIG. 1, respectively.
Referring to FIG. 1, the prior art steering column lock assembly shown therein comprises a lock housing 3 including a cylindrical block 1 and a generally U-shaped mounting block 2 through which the lock assembly is secured to an automobile steering column in which a steering shaft rotatably extends. The cylindrical block 1 accommodates a cylinder lock 4 at one end thereof and an ignition switch assembly 5 at the opposite end thereof and also accommodates a semi-circularly cross-sectioned locking bolt 6, which can selectively protrude into and retract from the U-shaped recess in the mounting block in a direction perpendicular to the longitudinal axis of the cylindrical cylinder block 1 respectively for locking and unlocking the steering shaft, which locking bolt 6 is located within an intermediate space between the cylinder lock 4 and the ignition switch assembly 5. This locking bolt 6 is normally biased by a compression spring 7 so as to assume a locked position in which the locking bolt protrudes into the U-shaped recess to lock the steering shaft and is operatively coupled to a cam member 8 rotatable together with the key plug part of cylinder lock 4, said cam member 8 having an actuating projection integrally formed therewith and operatively coupled to a rotor 9 of the switch assembly 5 for controlling the latter according to the direction of rotation of the key plug cylinder lock 4 which is effected by turning a mating key inserted in the cylinder lock 4.
The prior art lock assembly also comprises a retaining mechanism for retaining the locking bolt 6 in an unlocked position once the locking bolt 6 has been moved thereto by the rotation of the key plug of cylinder lock 4 in one direction and so long as the key is not removed or withdrawn from the cylinder lock 4 even though the latter has subsequently been rotated in the reverse direction back to the original position, but permitting the locking bolt 6 to return to a locked position upon withdrawal of the key from the cylinder lock.
In the construction described above and shown in FIG. 1, a relatively complicated and time-consuming procedure is required to assembly the various component parts together to provide a complete steering lock assembly. By way of example, relative to the cylindrical block 1, the cam member 8 and the cylinder lock 4 are successively subassembled and mounted in a direction shown by A from one end of the cylindrical block 1, the locking bolt 6 and the compression spring 7 are successively mounted in a direction shown by B, and the ignition switch assembly 5 is mounted in a direction shown by C and counter to the mounting direction A. This three-direction assembly system requires not only the complicated and time-consuming assemblying procedure, but also the increased number of the component parts of the lock assembly which in turn results in the increased weight of the lock assembly.
Specifically, the three-direction assembly system requires the use of separate fixing elements or fixtures to hold the respective component parts in position and, depending on the arrangement of the fixtures, some component part of the lock assembly has to be made of separate members. This will be explained by way of example with still reference to FIG. 1.
In order to secure a sufficient stroke of movement of the locking bolt 6 between the locked and unlocked positions, the cylinder lock 4 and the cam member 8 have to be made of separate members and such is the case with the prior art lock assembly shown in FIG. 1. In addition, in order to connect the cylinder lock 4 effectively with the cam member 8 so that the rotation of the key plug in cylinder lock 4 can be transmitted to the locking bolt 6 through the cam member 8, that portion of the cam member 8 which is connected to the cylinder lock 4 must be of a relatively large diameter, requiring the employment of a relatively large chamber in the cylinder block 1 for the accommodation of the cylinder lock subassembly so that the cam member 8 can be inserted into the intermediate space through the large chamber. The employment of the large chamber for the cylinder lock 4 necessitates the employment of a cylinder outer or sleeve 13. The outer cylinder or sleeve 13 forms a discrete part of the cylinder lock 4 together with a barrel rotatably housed within the sleeve 13 and is, after having been inserted into the large bore in the cylindrical block 1, held in position by means of one or more cotter pins 14. Furthermore, in order to retain the ignition switch assembly 5 in position inside the cylindrical block 1 at a position on one side of the locking bolt 6 opposite to the cylinder lock 4, the lock housing 3 is required to be formed with a partition wall 15 separating the intermediate space from a chamber for the ignition switch assembly 5 and to which the ignition switch assembly 5 is, after having been inserted into such chamber, engaged to assume a proper position inside the cylindrical block 1.
As best shown in FIG. 2, the retaining mechanism employed in the steering lock assembly shown in FIG. 1 comprises a locking lever 16. This locking lever 16 is movably accommodated within a slot 17 defined in the cylinder 13 and extending in a substantially intermediate portion of said cylinder 13 in a direction axially thereof, said slot 17 extending completely through the thickness of the wall of the cylinder 13. This locking lever 16 is held in position inside the slot 17 by inserting it exteriorly of the cylinder 13 together with a biasing spring 18 prior to the cylinder outer or sleeve 13 being inserted into the chamber in the cylindrical block 1 together with the barrel.
The particular configuration of the locking lever 16 employed therein constitutes an additional reason that the use of the discrete cylinder 13 is essential in the construction shown in FIGS. 1 and 2.
In addition thereto, considering the method for mounting the locking link 16 together with the biasing spring 18 on the cylinder 13, since the locking lever 16 is not fixed, but movably supported in the slot 17 and since the locking lever 16 within the slot 17 is spring-loaded, there is a possibility that the locking lever 16 may jump or scatter out of the slot 17 during the insertion of the assembly of the component parts of the cylinder lock 4 into the chamber in the cylindrical block 1.
As hereinbefore discussed, the prior art construction shown in FIGS. 1 and 2 requires the complicated and time-consuming procedure to assembly the steering column lock assembly.